Surfactants (also called surface active agents or wetting agents) are organic chemicals that reduce surface tension in water and other liquids. There are hundreds of compounds that can be used as surfactants. These compounds are usually classified by their ionic behavior in solutions: anionic, cationic, non-ionic or amphoteric (zwitterionic). Each surfactant class has its own specific physical, chemical, and performance properties.
Surfactants are compounds composed of both hydrophilic and hydrophobic or lipophobic groups. In view of their dual hydrophilic and hydrophobic nature, surfactants tend to concentrate at the interfaces of aqueous mixtures; the hydrophilic part of the surfactant orients itself towards the aqueous phase and the hydrophobic parts orients itself away from the aqueous phase into the second phase.
The hydrophobic part of a surfactant molecule is generally derived from a hydrocarbon containing 8 to 20 carbon atoms (e.g. fatty acids, paraffins, olefins, alkylbenzenes). The hydrophilic portion may either ionize in aqueous solutions (cationic, anionic) or remain un-ionized (non-ionic). Surfactants and surfactant mixtures may also be amphoteric or zwitterionic.
Surfactants are known for their use in personal care products (e.g., soaps, specialty soaps, liquid hand soaps, shampoos, conditioners, shower gels, dermatology and acne care products), household products (e.g., dry and liquid laundry detergents, dish soaps, dishwasher detergents, toilet bowl cleaners, upholstery cleaners, fabric softeners), hard surface cleaners (floor cleaners, metal cleaners, automobile and other vehicle cleaners), pet care products (e.g., shampoos), and cleaning products in general. Other uses are in industrial applications in lubricants, emulsion polymerisation, textile processing, mining flocculates, petroleum recovery, wastewater treatment and many other products and processes. Surfactants are also used as dispersants after oil spills.